Xing Zheng

Copper-catalyzed trifluoromethylation of alkenes with an electrophilic trifluoromethylating reagent

Summary An efficient method for the copper-catalyzed trifluoromethylation of terminal alkenes with an electrophilic trifluoromethylating reagent has been developed. The reactions proceeded smoothly to give trifluoromethylated alkenes in good to excellent yields. The results provided a versatile approach for the construction of Cvinyl–CF3 bonds without using prefunctionalized substrates.

Cross-Coupling between Difluorocarbene and Carbene-Derived Intermediates Generated from Diazocompounds for the Synthesis of gem-Difluoroolefins

Cross-coupling between difluorocarbene and carbene-derived intermediates generated from diazocompounds was developed to give gem-difluoroolefins, which constitutes a fast practical pathway to achieve hindered gem-difluoroolefins. The cross-coupling between difluorocarbene and aryl diazoacetates proceeded smoothly in the presence of a copper source, whereas its coupling with diaryl diazomethanes occurred well under metal-free conditions. A mechanism involving a copper-difluorocarbene complex was proposed.

A near-infrared BODIPY-based fluorescent probe for the detection of hydrogen sulfide in fetal bovine serum and living cells

A near-infrared (NIR) “off–on” fluorescent probe BDP-680 was developed by taking advantage of the Michael addition reaction of unsaturated double bonds in conformationally restricted BODIPY to allow detection of H2S. The new probe possesses a highly selective and sensitive response to H2S. Such a NIR probe has been applied successfully to detect H2S in 10% deproteinized fetal bovine serum (FBS). The detection limit of the probe for NaSH in 10% deproteinized FBS sample was calculated to be about 1 μM which is consistent with the value obtained from serum free solutions (0.5 μM). The probe is of low toxicity and has been successfully used to detect H2S in living cells.

Mechanisms of drug release in pH-sensitive micelles for tumour targeted drug delivery system: A review

During the past decades, chemotherapy has been regarded as the most effective method for tumor therapy, but still faces significant challenges, such as poor tumor selectivity and multidrug resistance. The development of targeted drug delivery systems brings certain dramatic advantages for reducing the side effects and improving the therapeutic efficacy. Coupling a specific stimuli-triggered drug release mechanism with these delivery systems is one of the most prevalent approaches for targeted therapy. Among these approaches, pH-sensitive micelles are regarded as the most general strategy with advantages of increasing solubility of water-insoluble drugs, pH-sensitive release, high drug loading, etc. This review will focus on the potential of pH-sensitive micelles in tumor therapy, analyze four types of drug-loaded micelles and mechanisms of drug release and give an exhaustive collection of recent investigations. Sufficient understanding of these mechanisms will help us to design more efficient pH-sensitive drug delivery system to address the challenges encountered in targeted drug delivery systems for tumor therapy.

Synthesis and antioxidant activity of curcumin analogs.

Abstract Numerous biological activities including antioxidant, antitumor, anti-inflammation, and antivirus of the natural product curcumin were reported. However, the clinical application of it was significantly limited by its instability, poor solubility, less body absorbing, and low bioavailability. This review focuses on the structure modification and antioxidant activity evaluation of curcumin. To study the structure–activity relationship (SAR), five series of curcumin analogs were synthesized and their antioxidant activity were evaluated in vitro. The results showed that electron-donating groups, especially the phenolic hydroxyl group are an essential component to improve the antioxidant activity.

Synthesis and evaluation of antitumour activity in vitro and in vivo of chrysin salicylate derivatives

Abstract A series of chrysin salicylate derivatives as potential antitumour agents were synthesised and evaluated their antitumour activities in vitro and in vivo. Most of the compounds exhibited moderate to good activities against MCF-7 cells, HepG2 cells, MGC-803cells and MFC cells. Among them, compound 3f showed the most potent activity against MGC-803 cells and MFC cells with IC50 values of 23.83 ± 3.68 and 27.34 ± 5.21 μM, respectively. The flow cytometry assay reconfirmed that compound 3f promoted the occurrence of tumour cells’ G1/S block under the inhibiting effect of compound 3f. Compound 3f possessed higher antitumour efficacy in tumour-bearing mice, compared with the positive control 5-Fu and the blank control saline.

Design, synthesis and biological evaluation of flavonoid salicylate derivatives as potential anti-tumor agents

A series of flavonoid salicylate derivatives containing trimethoxybenzene and a series of chrysin salicylate derivatives were synthesized for use as anti-tumor agents, and evaluated for antiproliferative activity using three human tumor cells: MCF-7 (breast carcinoma cells), HepG2 (liver carcinoma cells), MGC-803 (gastric carcinoma cells) and the mice tumor cells MFC (forestomach carcinoma cells). A substituent group of a suitable size and the trimethoxybenzene had a certain influence on the bioactivity of the flavonoid salicylate derivatives. Compound 2 and its salicylate derivatives 7a–7g containing the trimethoxybenzene exhibited more antiproliferative activity. Among them, compound 7g displayed the most potent antiproliferative activity against MGC-803 cells and MFC cells with the concentration causing 50% inhibition of cell growth (IC50) values of 11.05 ± 1.58 μM and 13.73 ± 2.04 μM, respectively. The flow cytometry results showed that compound 7g caused the cell cycle to be arrested in the G0/G1 phase and induced apoptosis of MFC cells in a dose-dependent manner. Furthermore, compound 7g showed good anti-tumor activity in vivo. These results suggested that compound 7g could be a new, potent anti-tumor candidate which should be optimized and evaluated further.

Difluoromethylation of N-arylsulfonyl hydrazones with difluorocarbene leading to difluoromethyl aryl sulfones

The difluoromethylation of N-arylsulfonyl hydrazones with difluorocarbene generated from difluoromethylene phosphobetaine (Ph3P+CF2CO2−) to give various difluoromethyl aryl sulfones is described.

Synthesis and Anti-cancer Activities of Apigenin Derivatives

A novel series of apigenin derivatives with phloroglucinol or resorcinol as raw materials were synthesized according to Baker-Venaktaraman reaction and their in vitro inhibitory activities on colorectal adenocarcinoma (HT-29) and leucocythemia (HL-60) cell lines were evaluated by the standard methyl thiazole tetrazolium (MTT) method. The results of biological test showed that some of apigenin derivatives possessed stronger anti-cancer activities than apigenin. Compound 6 showed the strongest activity against colorectal adenocarcinoma (HT-29) and leucocythemia (HL-60) cell lines with IC50 valure of 2.03±0.22 µM, 2.25±0.42 µM, it was better than 5-FU (12.92±0.61 µM, 9.56±0.16 µM), which shows a potential compound for colorectal adenocarcinoma and leucocythemia.

Diastereoselective Synthesis of CF3-Containing Vicinal Diamines

The highly diastereoselective synthesis of CF3-containing vicinal diamines by a convenient two-step procedure without the need to isolate the intermediate products is described.